Table 3.

Mathematical Equation Constructed by Factor Analysis to Calculate the Global Respiratory Severity Score (GRSS)

$$\text{GRSS is}={\displaystyle \sum _{j=1}^9{X}_j{\beta }_j+c,c=\mathrm{6.46.}}$$

Here, Xj, where j = 1, 2, …, 9, denotes the clinical variables used in the analysis, and βj denotes the weights assigned to these variables as listed in the table below. Also listed in this table are mean imputation values for each variable that were applied to the 7 subjects with missing data.

Variable	β j	Imputed Valuea
General appearance	0.719	1.144
Wheezing	0.936	0.558
Rales/rhonchi	1.150	0.507
Retractions	1.360	0.691
Cyanosis	0.812	0.050
Lethargy	0.475	0.190
Poor air movement	0.735	0.134
Worst room air SaO2	–0.078	90.360
Maximum respiratory rate	0.034	57.015

Abbreviation: SaO₂, arterial blood O₂ saturation.

^aImputed values were defined as the mean value calculated using data from all subjects with available values. Mean imputation values for each variable were used for the 7 subjects with missing data.